Normally, a coolant supply system for a machine tool provides coolant flow at the headwall and at the tool holder. Typically, these coolant flow outlets are either on or off at the same time, since there is only one coolant pump serving these outlets and the pump is either operated on or off. Also, the coolant outlets are provided with manually operable valves that can be selectively turned on or off manually. However, there is no provision for automatically turning off selected coolant outlets during a particular phase of a preprogrammed automatic machining operation to increase coolant flow at a particular location in the machine tool.
In a computerized numerically controlled machine tool, the various machining operations to produce a specific part are typically preprogrammed by an operator. Operations such as drilling, facing, cut-off, etc. are done by the machine automatically without intervention from the operator. During these operations, coolant flows are needed to prevent the part and the tools from overheating, to provide a means of lubrication for the cutting tools, to minimize thermal growth for the part being machined and the cutting tool that could otherwise cause errors in the parts being machined, etc. Coolant flow typically would be maintained at the headwall and the turret outlets. Therefore, during a drilling operation, the headwall outlet which would typically be directing coolant flow on the outside of a workpiece would be on, including a coolant flow outlet that directs coolant flow to the inside of the workpiece.
During a drilling operation, or any inside diameter machining operation, it is advantageous to increase the coolant flow directed to the inside of the workpiece, where most of the work and energy are being expended. This feature is not currently available in prior art coolant supply systems.
There is therefore a need for a coolant supply system for a machine tool wherein coolant flow directed to a particular portion of a workpiece can be selectively increased to meet the demand of the machining operation.